The present invention relates to segmented film capacitors and more particularly to stack type film capacitors having segmented film electrodes.
Metalized film capacitors are typically roll type or stack type capacitors. For a typical roll type, each of two strips of dielectric film, a first dielectric strip and a second dielectric strip, have respective metalized electrodes deposited on an electrode side of the dielectric strip. The first metalized electrode deposited on the first dielectric strip extends to one edge, a first metalized edge, of the first dielectric strip, and a strip of unmetalized dielectric is left on the opposing side of the first dielectric strip. Correspondingly, the second metalized electrode deposited on the second dielectric strip extends to the opposite edge, a second metalized edge, and the second dielectric strip has a strip of dielectric film on the opposing side which does not have metalized film. The two dielectric strips with metalized electrodes are wound together forming a capacitor roll, the metalized electrodes being separated by the dielectric film. Each dielectric film strip thus has a marginal non-metalized area extending along one edge, a non-metalized edge, which is matched to the metalized marginal area and metalized edge of the other dielectric film strip. On one end face of the capacitor roll, the first end face, a first end conductor of electrically conductive material is electrically connected to the first metalized edge, and on the opposing end face, the second end face, a second end conductor of electrically conductive material is electrically connected to the second metalized edge. Hence, the first end conductor is connected to the first electrode and the second end conductor is connected to the second electrode.
For a stacked type film capacitor, a plurality of dielectric film strips with metalized electrodes, each dielectric film strip having a non-metalized marginal area, are stacked one on the other so that each dielectric layer is sandwiched between metalized electrodes, and metalized edges and non-metalized edges are alternated from electrode to electrode, or in pairs of electrode with polarity being switched for successive electrode pairs. An end conductor of electrically conductive material may be electrically connected to the respective metalized edges to establish electrical connection and induce polarity.
Commercialization and use of the roll type film capacitor has exceeded that for the stack type primarily due to the advantage the roll type capacitor has in manufacturing. However, it has a disadvantage in that the continuous nature of the electrodes provides that a fault in the dielectric film that separates the electrodes, results in damage spreading in the capacitor and to the failure of the capacitor. Accordingly, a roll type capacitor requires segmentation of the metalized electrodes with current fuse interconnection. Segmentation provides that a fault in the dielectric in one particular area will not result in gross failure of the capacitor.
A typical stack type film capacitor, due to the isolation of the conductive layers, does not suffer from a risk of a fault developing in one dielectric area spreading to the entire capacitor. In other words, a failure or a fault developing in a dielectric for one layer of the stack will damage that layer but will not result in damage spreading to other layers of the stack. However, the manufacturing difficulties in manufacturing a stack film capacitor has resulted in its disfavor in comparison to a roll type capacitor, especially roll type capacitors with various types of electrode segmentation.
Developing technology has led to the development of lighter, thinner, and higher conductivity materials for conductive components of capacitors. One such material is graphene. It is a high conductivity, highly mechanically flexible, thin, and light material than can be used as a preferred material for all of the conductive components of a capacitor, including the metalized film. For all purposes of this application, the term “metalized” film, shall be defined to include dielectric film upon which graphene or other non-traditional conductive materials are disposed.
It is an object of the present invention to provide a folded stack type metalized film capacitor which provides for the utilization of manufacturing techniques which are similar to the manufacturing technique of a roll type capacitor.
It is a further object of the present invention to provide a folded stack type metalized film capacitor which incorporates a continuous base element which may be manufactured by manufacturing techniques which are similar to the manufacturing techniques of a roll type capacitor.
It is a still further objective of the present invention to provide a folded stack type metalized film capacitor which incorporates a thin, flexible ceramic material layer for the dielectric, thereby providing for a substantial increase in the voltage that may be applied to the capacitor, and, hence, a substantial increase in the charge and the energy that may be stored in the capacitor, in comparison to other stack type capacitors and roll type capacitors.